Saliva Proteomic Analysis of Autoinflammatory Mucosal Diseases by Mass Spectrometry: ELISA Validation

Objectives: Saliva is an important diagnostic fluid that contains numerous proteins that may be associated with disease phenotype. Given that Behcet’s Disease (BD), Inflammatory Bowel Diseases (IBD) and Mucous Membrane Pemphigoid (MMP) are inflammatory mucosal diseases that manifest within oral ulceration, analysis of the saliva proteome offers the potential to develop early diagnostic and/or discriminatory biomarkers.
The aim of this study was to identify specific proteins that are uniquely correlated as well as specific to each disease and to validate the results performing a secondary and complementary technique- enzyme linked immunosorbent assay (ELISA)
Methods: Saliva was collected from each cohort (10 on each) and assessed for proteomic differences. Analysis with the Q Exactive instrument in the Advanced Mass Spectrometry Facility at the University of Birmingham was carried out. Proteome discoverer was used for data processing. Each protein’s function was reviewed using Uniprot programme and by DAVID to explore them collectively using gene ontology.
Results: Comparing diseased samples to HC, 16 proteins were increased and 27 were decreased. 6, 8 and 10 were uniquely increased and 12, 16 and 13 decreased in the BD, IBD and MMP cohorts respectively. Galectin 7 and Annexin A1 were over expressed in all 3 cohorts. In the BD group, over expression of the secretory leukocyte protease inhibitor SLPI was seen. Interleukin-1 and Immunoglobulins as well as Desmoyokin were increased in the MMP and IBD group respectively. ELISA has been performed to validate results in each identified protein.
Conclusions: This novel study has identified over and under expressed proteins specific to BD as well as uniquely correlated to IBD and MMP patients. The results could inform further studies which may develop novel diagnostic tools for these inflammatory diseases as it is more accessible to measure individual analytes of interest by antibody-based techniques (such as ELISA or lateral flow devices) than mass spectrometry.